In the LTE (Long Term Evolution) system, uplink data signals and uplink control signals are transmitted from a mobile terminal apparatus to a radio base station in a PUSCH (Physical Uplink Shared Channel) and PUCCH (Physical Uplink Control Channel). The uplink data signals and uplink control signals transmitted in the PUSCH and PUCCH are multiplexed with demodulation reference signals, which are used to perform channel estimation for synchronous detection in the radio base station.
In this case, between plural mobile terminal apparatus, common ZC sequences (Zadoff-Chu Sequences) are used as signal sequences of the uplink reference signals, and they are cyclically shifted in each mobile terminal apparatus. In cyclic shift, a last part of a predetermined sequence is added to the head thereby to generate a different signal sequence, and this is repeated to generate plural different signal sequences. Then, the ZC sequences are cyclically shifted in specific cyclic shift per mobile terminal apparatus so that reference signals from the plural mobile terminal apparatus are orthogonalized.